bonnesen



flimd States atent i T RAN SPOSITION INSULATGRS Elmer Johannes Bonnesen, West Orange, N. L, assignmto American Telephone and Telegraph y a corporation of New York Application November 30, 1956, Serial No. 93AM 4 Claims. (Cl. 174--19 i) This invention relates to insulators for telephone trans mission lines and more particularly to a multiple-groove composite type insulator for use in transposing open wire lines in high quality circuits.

One object of this invention is the provision of a multiple-groove composite type transposition insulator which tures are used to accomplish these transpositions; for example point-type transposition at cross-arms or pole supported fixtures are provided; also brackets having insulators mounted thereon are positioned in mid-span and multiple-groove insulators which may be supported on brackets or suitable supports at the required transposition position are also provided.

It has been common practice to use a multiple-groove two-piece insulator of glass or other vitreous material. This particular structure was necessary to facilitate manufacture of an all glass or vitreous insulator since to provide multiple-grooves therein with a suitable skirt between the grooves to provide a long leakage path, which is mandatory on high quality open wire lines, was not feasible or practicable inasmuch as the extending skirt prevented the use of known molding methods and to devise new methods would be prohibitive due to the cost involved. It has been known that two-piece multiple-grooved glass insulators have an inherent weakness where they are joined but since no other structures were available they have been used but maintenance has been high due to failure of the insulators.

This invention provides a multiple-groove transposition insulator which is as strong mechanically as a one-piece insulator and has a long leakage path between the conductors in the grooves, and furthermore is relatively inexpensive to manufacture.

In accordance with the preferred form of my invention, I have provided a multiple-groove vitreous insulator which has a composite structure, that is, the main body portion is constructed from a suitable vitreous insulating material, and the skirt portion which separates the wire grooves and assures a long leakage path therebetween is constructed from a non-vitreous material, for example wax impregnated rubber.

The invention will be understood more clearly from the following detailed description when read in connection with the accompanying drawing in which:

Fig. 1 is an elevational view partly in section of one embodiment of this invention, showing the structure of the skirt and its location with respect to the wire receiving grooves; and

Fig. 2 is a fragmentary view of a portion of a transmission line illustrating one method of utilizing the insulator of this invention.

As shown in Fig. l, the insulator comprises a body member 10 of suitable insulating material, preferably of glass or other vitreous material, having on its periphery the circumferential wire receiving grooves 11 and 12. The bottom of the member 10 is provided with the usual skirt 13 to provide a long leakage path between the insulator pin and the wires located in the grooves on the insulators. Located between the grooves 11 and 12 is a circumferential groove 14 in which is positioned a skirt member 15 which is constructed from a non-vitreous material such as wax impregnated rubber. Since the inside of the skirt member 15 has a diameter less than the diameter of the insulator at the groove 14, the skirt 15 will be .irmly positioned in this groove and cannot readiiy be displaced.

Due to the cross-section structure at the skirt 15 and the adjacent groove 16, a long leakage path is provided on the wires positioned in the wire receiving grooves The interior of the body member 10 is prosuitable internal threads 17 which are adapted to engage the external. threads of an insulator supporting pin l3, such as shown in Fig. 2, which may be of wood or metal.

While 1 have shown and described a preferred embodiment or" my invention, it is to be understood that various changes and modifications may be made therein without departing from the scope and spirit of the invention.

What is claimed is:

l. A transposition insulator for electrical circuits comprising a body member of insulating material having its lower portion outwardly flared, said body member having therein a pin receiving recess which extends from said lower portion only partially into the body member to provide an unbroken upper surface at the top of said body member, said body member having on its outer surface, a pair of spaced apart circumferential wire receiving grooves, a third groove intermediate said wire receiving grooves, and a downwardly depending skirt of elastic insulating material positioned in said third groove and extending beyond the periphery of the outwardly flared lower portion of the body member.

2. A transposition insulator for electrical circuits comprising a body member of insulating material having its lower portion outwardly flared, said body member having therein a pin receiving recess which extends from said lower portion only partially into the body member to provide an unbroken upper surface at the top of said body member, said body member having on its outer surface a pair of spaced apart circumierential wire receiving grooves one adjacent the top portion of said memher and the other adjacent the flared lower portion, a third groove intermediate the upper and lower wire receiving grooves, and a downwardly depending skirt of elastic insulating material positioned in said third groove and extending beyond the periphery of the outwardly flared lower portion of the body member.

3. A transposition insulator for electrical circuits comprising a body member of insulating material having its lower portion outwardly flared, said body member having therein a threaded pin receiving recess which extends only partially from said lower portion into the body member to provide an unbroken upper surface at the top of said body member, said body member having on its outer surface, a pair of spaced apart circumferential wire receiving grooves, a third groove intermediate said wire receiving grooves, and a downwardly depending skirt of wax impregnated elastic insulating material positioned in said third groove and extending beyond the periphery of the outwardly flared lower portion of the body member.

areaoee 4. A transposition insulator for electrical circuits comprising a body member of insulating material having its lower portion outwardly flared, said body member having therein a threaded pin receiving recess which extends from said lower portion only partiallyinto the body memher to provide an unbroken upper surface at the top of the insulator, said body member having on its outer surface a pair of spaced apart circumferential Wire receiving grooves, one adjacent the top portion of the insulator and the other adjacent the flared lower portion, a third tZite-d in the file of this patent UNiTED STATES PATENTS Slonecker June 24, hampion Mar. 10, Bott Nov. 8, Dehmel Nov. 29, Reed Dec. 16, Smith et al. Dec. 8, Shilling Feb. 23,

FOREiGN PATENTS Germany Dec. 19, Denmark July 23; Germany May 30, 

